Pneumatic reader for perforated media

ABSTRACT

A pneumatic, perforated tape, intermittent motion reader is connected to a pneumatic-to-hydraulic interface in a hydraulic control system. A hydraulically controlled pneumatic purge system is provided for ejecting or purging foreign matter from the pneumatic reading lines between successive cycles of reading by the reader, by blowing air under high pressure through the lines in the reverse direction to the direction air travels when the reader is reading. Reading is blocked during the purging cycle by locking diaphragms in the interface.

D United States Patent 1 1 1111 3,735,7'7i Panissidi 51 May 29, 1973PNEUMATIC READER FOR [56] References Cited PERFORATED MEDIA UNITEDSTATES PATENTS 5 paniss'di Peeksk'll 1,274,103 7/1918 Story ..137 240[73] Assignee: International Business Machines 2,827,767 3/1958 Hill..91/36 Corporation, Armonk, N .Y.

I Primary Exammer-Martm P. Schwadron Flledi 1970 AssistantExaminer-Richard Gerard [2].] AppL NO; 103,223 Attorneyl-lanifin andJancin Related us. Application Data 1 ABSTRACT [63] Continuation-impartof Ser. No. 824,424, May l4, A 'j perforated tape intermittent 1969reader 1s connected to a pneumat1c-to-hydraul1c interface in a hydrauliccontrol system. A hydraulically controlled pneumatic purge system isprovided for [52] US. Cl. .137/15, 137/239, 137/624.l8, ejecting orpurging foreign matter from the pneumatic Y I 235/201 FS reading linesbetween successive cycles of reading by I Int- Cl..... .i ..G06k thereader blowing air under pressure through Field of Search the lines inthe reverse direction to the direction air travels when the reader isreading. Reading is blocked during the purging cycle by lockingdiaphragms in the interface.

9 Claims, 5 Drawing Figures SENSE 1501111111; VALVE P PURSE CONTROLVALVEPATENIEL Z HH 3,735,771

SHEET 1 OF 5 FIG. 1

8CHANNEL TAPE R PILOT CONTROL VALVE 22o HYDRAULIC 242 T SIGNAL T0 PILOTVALVE DIAPHRAGM?) 224 PURGE CONTROLVAILVE IINVENTOR 227 226 HUG0A.PAN|SSIDII B M 1W ATTORNEY PATENIEL, HAY 2 91875 SHEET 3 BF 5 PATENIE7.7291975 SHEET S BF 5 FIG. 20

1 PNEUMATIC READER FOR PERFORATED MEDIA CROSS REFERENCE TO RELATEDAPPLICATIONS This application is a continuation-in-part of U. S. Pat.

.application Ser. No. 824,424' by H. A. Panissidi enti- BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates to fluidsensing means for sensing the presence of indicia in the form ofapertures in a record bearing medium and more particularly to means forejecting foreign material from the sensing .means.

2. Description of the Prior Art In the'prior art means have beenprovided for preventing foreign material from entering perforated recordpneumatic readers.

One such means includes a fluid jet stream from a first source generatedon one side of a record card, etc., which passes through an aperture orperforation in it to provide a jet stream of air to be directed towardsan orifice on the opposite side of the card. Connected to the orifice isa chamber continuously supplied with clean air from a second source sothat the static pressure in the chamber varies as a function of thevelocity of fluid flow through the orifice. A fluid pressure sensor isalso connected to a chamber. Sufficient space must be maintained at alltimes between the orifice housing and the record card for flow of theclean fluid even when an imperforate record card surface is positionedbetween the jet stream and the orifice. This provides for continuouspurging of contamination in the chamber. When the jet stream impinges onthe orifice, the pressure differential is measured by the sensor.Problems associated with this approach are that the orifices will tendto become clogged with oil and lint if no filter is used. If a filterwere used in a-factory environment, it would need to be cleaned veryfrequently and would have to be very elaborate to handle the kinds ofcontaminants present in a factory as opposed to a normal data processingenvironment.

The prior art has not shown meansfor using positive pressure singledirection pneumatic reading combined with positive pressure ejection ofcontaminants in the reverse direction.

SUMMARY OF THE INVENTION An object of this invention is to provide meansfor purging contaminants from a pneumatic reader for aperture codedmedia.

Another object of this invention is to'provide a positive pressurereader for sensing air pressure passing through aperture coded mediawherein the reader operates independently and intermittently.

Still another object is a purging system for such a reader wherein crosstalk through the purging circuit is eliminated during the reading cycle.

Yet another object of this invention is to release purging pressure inthe pneumatic circuit in a reader beforebeginning a reading cycle.

Another object'of this invention is to prevent reading of pulse dataduring pneumatic conduit purging cycles in a reader.

A further object is to clean the tape prior to reading the perforationstherein while transferring its position on a reader.

Still another object is to eliminate the use of filters in a pneumaticreader for perforated media.

In accordance with this invention, a pneumatic reader for perforatedmedia is provided in which an intermittent or periodic pneumatic purgingcycle is employed to eject foreign matter by employing a reverse flow ofair through the reader input lines between reading cycles.

Preferably sensors in the reader are disabled when the purging operationis being undertaken.

Further,'in accordance with this invention, cross talk is suppressed bymechanical means during reading. In another aspect, means are providedfor releasing pressure in the system prior to reading after purging thesystem.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a simple embodiment of apneumatic tape reader and air to hydraulic interface system in which anintermittent pneumatic purging system is employed.

FIG. 2 shows the arrangement of FIGS. 2A-2D which show an overallpneumatic and hydraulic system of the kind shown in FIG. 1 including afew modifications.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now madeto FIG. 1 which shows an embodiment of the present invention which isillustrative with 16 ports to read perforated tape codes representingcharacters from a plastic tape 11. The 16 ports of the air reader head10 are connected by sense hoses 12 to 16 diaphragms 102 drivinghydraulic pilot valves 13 only one of which is shown in FIG. 1. The airreader head 10, supporting the tape 11, is pressurized with 10 psig airpressure by a spring loaded air manifold 111. A hole in the tape 11 willallow its corresponding diaphragm actuated pilot valve 13 to bepressurized with 10 psig air pressure from the air manifold.

The tape 11 is driven by a sprocket wheel 118 engaging drive holes inthe tape 11. The sprocket 118 is attached to the shaft of the drive gear121. The angular position of the drive gear 121 is accurately maintainedby a spring loaded detent 124. When a hydraulic signal is applied online 242 to the right end of control valve 220, control valve 220 movesto the left against the re- 3 action Qfitsspring 22] allowing thepressure manifold port P 222 to be exposed to line 76, thus applyinghydraulic pressure to the end of land 136 of toggle valve 77, to movevalve 77 to the right against the reaction of its spring 138 causing thetoggle lever 126 to rotate counterclockwise to a vertical position. Thepin 128 attached to the toggle lever and contacting the lower surface orrack 125 will raise rack 125 to cause the rack 125 to engage the drivegear 121, while flexing its drive wire 129. The toggle valve 77, whichhas been driven to the right as described earlier, will expose its port139 to port P 116 applying hydraulic pressure to the left hand side ofthe drive piston 130 causing it to move to the right against thereaction of its spring 132 and rotating the drive gear 121 and sprocketwheel 118 counterclockwise advancing the tape 11.

With the hydraulic signal pressure on line 242 removed from the righthand side of the control valve 220, the control valve 220 will return toits initial posi- 1 tion by the reaction of its spring 221 exposing theport I 76 to R or a low pressure return line to the reservoir.

With pressure removed from the left hand 136 of the toggle valve 77, itsspring 138 will drive it to the left rotating the toggle lever 126 toits initial position. The

toggle valve 77 will expose port 139 to its port R, thereby removingpressure-from the left hand side of the drive piston 130'allowing it andits rack 125 to return to its initial position by the reaction of itsspring 132.

During the above tape advancing cycle, the pilot valve 13 of thehydraulic system must be physically locked by pressure on line 276 fromresponding to the tape holes as they move over the air reader head, andat the same time, the sense hoses, the diaphragms 102 and air readerports 12 must be flushed out with a reverse air blast to purge thepneumatic sensing system of any contamination introduced during theprevious reading cycle. With a hydraulic signal applied to the righthandend of the control valve on line 242, it will move to the leftagainst the reaction of its spring 221 exposing line 76 to its pressureport P 222 applying pressure to the left end of the toggle valve 77affecting the tape drive as described earlier. Simultaneously it appliespressure on line 276 to the left end 85 of all the pilot valves 13 ofthe hydraulic system, preventing them from moving during the tapeadvancing period.

At the same time, line 76 is connected to the left ends 96 and 96 of thepurge control valve 99 and isolating valve 98 respectively causing bothvalves to move to the right against the reaction of their respectivesprings 223 and 108. The transfer of the multiple land isolating valve98 will expose all of the purge hoses 101 to the Ppo'rt 225 of thetransferred purge control valve 99 via lines 235, and the cylinder 236carrying valve 99. At the same time, it shuts off the air pressure tothe air manifold by the scissoring action between line 110 and source109 by the extreme right hand land 224 of the isolating valve 99.

Because the P port 225 of the purge control valve 99 is connected to aten psig air pressure source, it provides a high velocity reverse airflow through the sixteen diaphragm chambers 102, sense hoses l2 and theair reader head ports. Thus, any foreign matter, is expelled between theair reader head 10 and tape 11 to the atmosphere. For purging of foreignmaterial from sense lines 12, air under pressure is driven up throughline 101 from isolating valve 98 through the input chambers of valves102 to blow air in reverse up through the line 12 and under or throughthe tape 11 which is held down by manifold l 1 1 which is positioned byspring 117. Foreign matter is expelled between the tape and the membersof air reader 10 as the air escapes. The spring is strong enough to holdthe paper down. The spring is sufficiently weak to permit air carryingforeign matter to escape between the tape 11 and the parts of the reader10. Following the purge cycle, the entire reading circuit and diaphragms102 must be depressurized before releasing the locked diaphragm actuatedpilot valves 13. In order to accomplish the depressurization, the purgecontrol valve 99 must be returned to its initial left hand positionbefore the return of the isolating valve 98 sealing off all the purgehoses 101.

A time delay network consisting of an orifice 228 in series with a delaypiston 226 in cylinder 227 (connected to return 240 of valve 220 by line241 at one end) is introduced to the right hand end of the purge controlvalve 99. Although both ends of the purge control valve 99 are exposedto line 76, the pressure buildup or rise is delayed on the right handend 239 of the purge control valve 99 until the delay piston 226 hasmoved to the left with a time constant dependent upon cylinder length,its diameter and the size of the orifice 228. When the delay piston 226has traveled its predetermined distance, the pressure at both ends ofthe purge control valve 99 will be equal, therefore allowing thereaction of the spring 223 to return the purge control valve 99 to itsinitial position to expose all the purge hoses 101 to the atmospherethrough pneumatic return port R 229. Again, at the end of the tapeadvance cycle, the control valve 220 will be restored to its initialposition by the reaction of its spring 221 with the removal of thehydraulic signal on line 242 exposing line 76 to the low, reservoir,hydraulic pressure. This allows the tape advance circuit, and theisolating valve 98 to reset to'their initial positions. It releases thelocking pressure from the left hand ends of the pilot valves 13. I

Resetting of the isolating valve 98 admits air pressure from source 109into the air manifold 111 and, at the same time, seals the individualpurge hoses 10 to prevent cross talk between diaphragms 101 during thereading cycle as with the several diaphragms 101 which are shown inFIGS. 2A-2D. With the release of the locking pressure on line 276 fromthe pilot valves 13, the diaphragms 102 can respond to a hole in thetape 11 causing the transfer of the associated pilot valve 13 againstthe reaction of its spring 230. Thus,- data in the form of holesperforated on a tape controls the pilot valves 13 in a hydraulic system.

Lands 96, 231, 96', 234, 237 and 239, as well as 0 rings 230, 233 and238 provide separation of the hydraulic and pneumatic systems. Vents232, 234 and 199 assure protection against pressurized air passing intothe hydraulic system.

CONTROL SYSTEM Reference is now made to the control system shown inFIGS. 2A-2D which is shown and described in greater detail in mycopending U. S. application Ser. No. 824,424. The system includes an airreader 10 for reading a perforated tape 11 which provides output pulsesto a hydraulic control system by means of air lines 12 (FIG. 2C)connected to air hydraulic internected via lines 141, 142 to extend orretract a corresponding one of piston adders which compriseinterconnected pistons and cylinders employed to provide V binarydisplacement of load bearing shaft 156 by unit distances. 1

A set of variable orifices in a velocity control valve (not shown butconnected to line 94) are provided between lines 142 and 342 for thepurpose of controlling the rate of displacement of the pistons.

In order that the pistonadders and an output shaft connected to one endthereof may be accurately located rapidly, a damper, shown in mycopending application is provided which permits the piston adders tocock itduring an exchange interval.

The exchange interval is a time during which the output shaft is firmlyretained in position by braking means shown in part in FIG. 4 of my U.S. application Ser. No. 824,424 and in detail in my copending U. S.application Ser. No. 694,941 entitled Manipulator and the piston addersare reset and extended to the extent that certain pistons are retractedand certain other pistons are-extended. During the exchange period thevelocity control valve will be held wide open to permit exchange atmaximum permissable velocity, since the piston adders will not be underload. The flow system 23 includes restrictive passageways 42, 44, 49 andorifices 50 and restrictive bypass valve 41 for varying the resistanceof flow of fluid through line 52 and latch valves 14 and lines 141 and142 of the hydraulic circuit to the piston adder drive. A hydrauliclogic unit responds to an output of system 23 on line to close valve 40to increase the resistance to flow through system 23 to the piston adderdrive and to release braking means controlled by aligner lines shown inSer. No. 824,424. Exchange piston 35 and move piston 36 biased bysprings 43 respond to decline of flow velocity below a predeterminedlevel to cause lines 24 and 25 to sense such decline by disconnectingthose lines from a zero pressure return line 46. The move pistonoperates with line 24 for sensing the termination of a step of operationof the arithmetic piston adder drive.

In order to provide regulated hydraulic pressure to the system in mycopending application Ser. No.

. 824,424, a hydraulic power supply is provided. It

supplies hydraulic pressure for latching of spool valves on lines 600and 116 and to the central lands 16 of spool valves in the hydrauliclogic unit 20 via line 116. Pressure-is also supplied to the flowsensing system 23, via line 47, which controls two bleed lines 24 and 25to the hydraulic logic unit 20. The flow sensing system 23 operates as afunction of the velocity of flow through line 47, the flow sensingsystem 23 and line 52 to the latch valves 14 which connect to the pistonadders. When the flow or displacement of piston adders declines below aminimum value the bleed lines 24 and 25 are blocked by flow sensingsystem 23. A bypass control line 38 from the hydraulic logic unit 20controls a port 40, 41 inside the flow sensing system 23 to control oneof the flow sensing units therein.

The hydraulic logic unit 20 can be started and stopped. Since the logicunit 20 controls the toggle line 76 in FIG. 2A which powers the feedadvance of the tape reader shown in my copending application Ser. No.824,424 when switch 54 is operated, air is blocked from operating thelogic unit 20 and, at the end of a displacement cycle operation of thesystem stops. Line 94 adapted to connect to operate aligners not shown,which are similar to those shown in my copending United States patentapplication Ser. No. 694,941.

A set of sweep sense units 33 and a sweep cylinder 34 turn or sweep aload on support about an axis upon an input via line 198 or 200 from oneof the latch valves 14. The sweep sense unit 33 is connected to bleedline 25.

EXCHANGE AND VARIABLE VELOCITY CONTROL The exchange and move flowsensing system 23 includes a cylindrical exchange sense piston valve 35,a cylindrical exchange move sense set valve 36 and a by pass poppet 37.The bypass poppet 37 is controlled by pressure in a line 38 connected tothe lower output of flow spool valve 39 in FIG. 2B. When pressure inline 38 is above return pressure, it drives piston 37 to the right toopen valve 40 by moving it away from surface 41. When there is nopressure in line 38, which results when line 38 is connected to a zeropressure return line, as via groove 95, when valve 39 is down, thenpiston 37 moves left closing valve 40.

When the bypass poppet 37 is to the left, its valve 40 will seat onsurface 41 to close off the inlet 42 to the exchange sense piston 35. Itshould be noted that the exchange sense piston 35 and the move sensepiston 36 are each spring biased by springs 43, coaxial therewith in thelarger coaxial bore 44 in the pistons 35 and 36. The pistons 35 and 36have annular grooves 45 to connect the bleed lines 24 and 25 to thereturn 46 to the low pressure side of the hydraulic pressure supply 22.

When piston 35 blocks bleed line 25 from return 46, as the result of alow flow rate through orifice 50 of piston 35, then after a time delayhydraulic logic 20 removes pressure from line 38, by driving flow spoolvalve 39 down which pulls piston 37 left to close valve 40- on surface41.- Valve 39 connects line 38 to zero pressure, i.e., return pressurevia groove 95. Pressure from a hydraulic pressure supply shown in Ser.No. 824,424 is supplied by line 47 to the inlet 48 on the upstream endof the valve 40 of the bypass poppet 37 which mayor may not be open, asdescribed above, and to the inlet 49 to the move sense piston 36.

Hydraulic line 47 is connected to hydraulic line 52 through system 23via inlet 48, which connects via inlet 49, orifice 50, coaxial bore 44,and line 51 connected to line 52, and in parallel, when valve 40 isopen, through inlet 48, through port 41, past valve 40, through inlet42, through orifice 50, through coaxial bore 44, and through line 51 toline 52 also. Each of the exchange sense piston 35 and the move sensepiston 36 is provided with a smaller axial bore 50 to the upstream endthereof confronting the corresponding inlet 42 or 49 thereof. Theorifices 50 are selected so that when the pressure differential acrossthe orifice 50 is above a predetermined level, then the pistons will bedriven upwardly against the pressure of the springs 43 to align thegrooves 45 with the bleed lines 24 and 25, thereby connecting the bleedlines to return 46. The bypass poppet 37 provides a means forselectively actuating the exchange sense piston 35. In this way, theflow sensing system may be operated in two modes depending on whetherthe piston adders are being driven in the move or exchange mode ofoperation.

A further feature is that each orifice 50 is of the same order ofmagnitude in diameter and length, so the resistance to fluid flowprovided by each thereof is of the same order of magnitude. When bothare connected in parallel, the resistance to flow provided by eachthereof is of the same order of magnitude. When both are connected inparallel, the resistance to flow is nearly halved, or conversely, flowdoubles, approximately. As will be noted, the outlets 51 of the twosense pistons are connected to line 52. Since the two sense pistons arein parallel, and therefore the orifices 50 are in parallel, if thebypass valve 40 is open, the quantity of flow through each of the twoorifices 50 will be substantially equal and accordingly the rate of flowinto the line 52, if sufficiently large and unrestricted will in generalbe approximately doubled. Accordingly, when the exchange sense piston 35is permitted to operate by the bypass poppet 37, the-quantity of fluidflowing from lines 51 through line 52 to the piston adder drive will begreater and the velocity of displacement in the exchange period willaccordingly be far greater.

HYDRAULIC LOGIC UNIT The hydraulic logic unit contains many types ofelements. These include a plurality of spool valves, delay pistons incylinders which require a time delay for displace-ment from one end tothe other end of the cylinder in which they are housed, orifice checkunits shown in FIG. 2L of my copending application Ser. No. 824,424,interconnections and outlets which control other elements of the overallsystem. Certain spool valves are spring-biased into one position asindicated by helical springs in longitudinal cross section, Certainother of the spool valves are latch valves which areheld in position byhydraulic latching means. Such a latching means comprises a passageway600 tangential to one end of a land of a spool located so that itsupplies fluid under pressure to the side of the land regardless ofspool position, and contacts a small area on one side. The land therebycreates a laminar pressure gradient along that side which is coupled tothe return lines through leakage. There is a ratio of pressures acrossthe land of several times the pressure on the low pressure side whichpushes the land to one side and inhibits longitudinal sliding because offriction forces. Pressure can be relieved during movement of the spoolsto relieve friction forces.

When pressure at inlet 53 coupled from the tape reader actuated by startapertures 28 in the tape 11 via line 29, it operates the start diaphragm56 (assuming pneumatic toggle 54 is on) or otherwise provides input froma two way solenoid or valve 27, etc. then the start spool valve 55 movesup. This movement connects its lines 57 to the right and to the left tohigher pressure from the central annular groove 16 of valve 55 as thecentral land or ring passesthereabove. Pressure is applied at thejunction 58 between the orifice checks (see FIG. 2B) 59 and 60 whichconnect to the probe spool valve 61, the probe delay piston 62, and theprobe phase piston 63.

On the left side, the line 57 connects to the point 64 v to supply thelower end of flow spool valve 39; and by connection through orificecheck 65, point 64 connects to line 66 and phase piston 67. Note thatorifice check 65 is located differently from orifice check 70.

It will be noted that line 66 connects to bleed line 25 and both connectto the upper end of the flow spool valve 39, which is spring-biaseddown. However, pressure at point 64 biases the valve 39 up until line 66is pressurized. When the flow phase piston 67 has moved fully to the topof its cylinder at the end of 60 milliseconds, and when exchange sensepiston valve 35 disconnects bleed line 25 from return 46, the pressureon the line 25, and at the top of flow valve 39 increases and the flowvalve 39 is pushed down hard to return to its position as shown in FIG.2B under the force of the spring 87. The time delay is set by theorifice and piston 67.

Initially, after start valve 55 operates, flow valve 39 operates andpressure is placed on line 38. Then line 38 connects pressure to thebypass poppet 37, which remains open until the flow valve 39 returns tohome position. Since line 38 is connected to the lower end of delaypiston 68 and to the lower end of move spool valve 69, which is biasedupwardly, the move valve 69 moves up fast shortly after the flow valve39 moves up, by spring 53.

Later, when flow reverses, the delay piston 68 cooperates with theorifice check 70 to provide a long time delay before the move valve 69can be reset down against the force of its spring 53. When the movevalve 69 is driven up, the line 71 from the upper end of valve 69 hasthe pressure thereon released, thereby releasing pressure on the top ofthe exchange valve 72. Valve 72 has pressure on the lower end thereofapplied on line 38. After the delay valves 68 and 105 permit thepressure to build, valve 72 will then shift upwardly. The damp spoolvalve 73 has a spring bias at the lower end thereof, and will shiftshortly after the exchange valve 72 shifts, thus releasing the pressurefrom its upper end. Line 75 is connected to the damper including itspistons secured to one end of the piston adders. Then in eachdisplacement cycle of the drive, pressure is released from the damperpositioning pistons. The damper is released to be cocked duringexchange.

After about 20 milliseconds to position pilot valves 85, the probe delaypiston 62 reaches the opposite end of its cylinder. Then the pressure onthe lower end of probe spool valve 61 reaches a high enough level toovercome the spring biasing force at its top to drive the valve 61 toprovide pressure on probe line 81 from the central annular pressuresource 82 as the central land passes thereacross and the lower landpasses across the return 83.

The probe line 81 is connected to probe of the inlets 84 of the pilotvalves 85 to provide pressure to their central annular cavities. Theprobe pressure is employed to adjust the hydraulic binary latch valves14 in accordance with the binary valves provided by the air, tape reader10. The binary drive is reset by the most recent input data provided bythe tape reader 10.

About 40 milliseconds after start, probe phase piston 63 rises to thetop of its cylinder and causes a pressure build up at its lower end,connected to the top of probe spool valve 61 which is spring-biaseddown. Since the pressures of the opposite ends of the probe spool valve61 will be equal and opposite, the probe valve is moved down by itsspring 86. Then pressure is removed from probe line 81. This does notend the exchange motion of the piston adders which are controlled byhydraulic latch valves 14 which remain as positioned during the probeportion of the control cycle of the hydraulic logic circuit 20. Whileexchange continues, the exchange sense piston valve 35 remains againstit spring like move sense piston valve 36.

'When exchange velocity substantially ends resulting in elimination ofsubstantial pressure differential the flow through the sense pistons 35and 36 ends, substantially, they move down to their spring biased lowerpositions. Then bleed line 24 closes momentarily and bleed line 25closes for the remainder of each cycle of operation of the hydrauliclogic unit 20. Line 25 then builds up pressure on the upper end of theflow valve 39 and its top spring 87 pushes flow valve 39 down..

Pressure builds on line 24 and line 89 from lines 16 and 688 through theflow valve 39. However, the delay piston 68 and the orifice 703 inorifice check 70 defers the build up of the pressure in the lines 24 andthe build up of the pressure in inlet 89 to a level sufficient to pushmove valve 69 down. Move valve 69 will not operate after exchangebecause move sense piston 36 reconnects bleed line 24 to return 46 tobleed pressure from inlet 89 before sufficient time passes to build upenough pressure in inlet 89. Line 688 applies pressure immediately tothe central cylindrical cavity 188 of the exchange spoolvalve'72 held upby pressure in line 38 to provide pressure on line 90 to the lower endof the aligner latch valve 74. Low pressure on line 75 and high pressureon line 90 drives the aligner latch valve 74 up.

The aligner lat'ch valve 74 releases pressure on line 91 so spring 93drives aligner valve 92 up. This applies pressure to line 189 resettingstart valve 55, applying pressure from line 116 to reset line 88 toreset all of the pilot valves 85 and will release pressure from line 94which is to be connected to load aligners to move the output load. Line94 also connects to the velocity control valve 17 to move it to reducethe orifice into the piston adders 15 during the period of driving ofthe load. Now the load can move so the piston adders can move and flowresumes in line 52. Thus the pressure drop across the move sense pistonvalve 36 resumes and move sense piston valve 36 moves up again to bleedpressure from the bleed line 24.

Pressure on the control line 38 for bypass poppet 37 is released sincetheflow valve 39 is down to connect line 38 to the return 95. Pressureon line 76 connected to reader from aligner latch valve 74 in FIG. 2A isintended to operate the tape reader feed mechanism. In

' addition, in a purge control shown in my copending application Ser.No. 824,424 pressure in line 76, will operate a pair of pistons 96 fromline 97 attached to the line 76 to drive the spool valves 98 and 99 tothe left so that the pressure on line 100 will be connected down intothe lines 101 which are connected to the purge inlets to the diaphragms102 in the air hydraulic interfaces 13 in, FIG. 2C. Air under 10 psigpressure blows through the purge inlets 10] across the surface of thediaphragms of the interfaces 102 and out through the reader lines 12 topurge or to drive oil from the system and to clear chad and othermaterial from the lines 12 and 1 12.

Pressure remains on line 76 until the piston adders stop and move valve69 moves when bleed line 24 closes as move sense piston 36 moves down.Then, line 71 drives exchange valve 72 down removing pressure from line90 and applying pressure to line 103 through 10 the orifice of orificecheck 104 and delay piston 105, after a'time delay of milliseconds,which pressure drives the damp valve 73 down against its spring. Valve73 applies pressure on line 75 to drive the aligner latch valve 74 downand remove pressure from line '76 and to apply pressure to line 91 andthrough the orifice in the orifice check 106 and delay piston 107require a time delay to pass before pressure drives aligner valve 92down against its spring 93. The aligner delay piston 107 requiresanother 120 milliseconds to drive downwardly.

However, referring again to the purge unit, when line 71 is pressurized,a piston 99 is shifted right so atmospheric pressure from line 99, toatmosphere will be permitted to resume inside the purge and reader lines101 and 12 to return diaphragms 102 to atmospheric pressure. Then whenpressure is removed from line 76 as a result of return of the alignerlatch valve 74 to its lower position, the spring 108 of the spool valve98 will act to drive that spool valve to the right and to shut offconnections 101 to the diaphragms. It should be noted that the 10 psigair supply 109 is connected to line 1 10 which applies positive pressureto the air pressure head 111 for passage through the tape 11 into theinlets 12 to the diaphragms 102.

During the time that the purge spool valve 98 is to the left, theblocking of pressure by valve 98 from line 110 to the air reader 1 11will prevent blowing air down into the diaphragms 102 during the purgecycle when air is to be blown in the reverse direction.

The perforated tape reader shown in FIG. 2 will operate in ordinarymachine shop air typical of industrial locations, which is contaminatedwith dirt, oil and water. Cyclic purging of lines 12 is necessarybecause the reader sense hoses are extremely thin, usually 0.030 inchesI.D. making them vulnerable to clogging.

In order to avoid costly memory devices and serial to parallelconverters for some applications, the reader is designed to advance thetape up to two characters per step, allowing the system to accept twocharacters of data simultaneously. The hydraulically driven reader, asshown schematically, consists of an air reader head with 16 ports toaccept two perforated characters of an 8 channel Mylar tape. The 16ports of the air reader head are connected by sense hoses to the 16diaphragm driven hydraulic pilot valves. The air reader head, supportingthe tape, is pressurized with 10 psig air by a spring loaded airmanifold. A hole in the tape pres surizes its corresponding diaphragmactuated pilot valve with 10 psig from the air manifold.

The air reader 10 includes an air pressure head 111 which is springbiased downwardly by a spring 1 17. The tape which is used includeseight longitudinal columns and is read in groups of two rows ofcharacters such, as shown in FIG. 2D, simultaneously. Accordingly, thefeed must advance two rows of holes for each reading cycle. The top holein the first row is the start control. The next two holes are M2 and M1controls for FIG. 2E and the next holes ones are the fractions fromonehalf inch down to one thirty-second inch. In the second column in thesecond hole, the sweep mode of operation of the manipulator which wouldbe attached to the device is entered and in the third hole, the bit forthe grip mode of operation of a manipulator gripper would be entered. Inthe last five holes in the second column, the bits forthe 16, 8, 4, 2and 1 inch piston adders would be entered. The head 111 is designed soas to I provide air pressure above all 16 holes and underneath the holeswould be aligned the various inlets 12 to the diaphragms 102 shown inFIG. 2D.

The feeding mechanism is comprised of a sprocket wheel 118 whichoperates in cooperation with perforations 119 in the tape 11. Thesprocket wheel 118 is secured to shaft 120 and the shaft 120 isjournalled for rotation in response to torque applied by' gear 121 whichis retained in position by detent pawl 122 which is spring-biaseddownwardly by spring 123. The pawl 122 carries a pin 124 at one endthereof which fits into the teeth of gear 121. v

The gear 121 is adapted to mesh with a rack 125 which can be raised intogear by a toggle lever 126 which is pivotally secured by pin 127 inwhich toggle lever carries rack 125 on pin 128. The rack 125 isreciprocably longitudinally slideable on drive wire 129 secured at itsdistal end to a piston 130 slideably carried in cylinder 131 forlongitudinal reciprocation therein.

The cylinder 13] contains a spring 132 at the distal end of the piston130 for biasing the piston 130 leftwardly. At the opposite end of thecylinder is a release aperture 333 to permit motion to the right. Theopposite end of the toggle lever 126 is secured to a drive wire 133 bymeans of pin 134 to bifurcated end 135 of drive 'wire 133. Drive wire133 is secured at its distal end to a spool valve 136 carried incylinder 137.

The spool valve 136 is spring-biased leftwardly by spring 138. At theleftward end of piston 130 is an inlet 139 connected from the centralportion of cylinder 137 adapted forcommunication with the two inlets 81and 281 into the lower cylinder 137 from the central portion thereof.

At the leftward extreme end of cylinder 137 is located an inlet fromline 76. Line 76 from the aligner latch valve lower outlet is providedfor starting operation of each cycle of the"reader. If pressure wereapplied to line 76, it would function to pull the toggle level 126counterclockwise about pin 127 by means of flexing of drive wire 133.Lever 126 and pin 128 will drive the rack 125 up into engagement withthe gear 121 preparatory to actual driving motion. When this occurs,i.e., valve 77 is to the right, the connection of line 139 to thecylinder 137 will be made to the line 116. This will drive the piston130 to the right against the reaction of its spring 132 pulling wire 129and the rack 125 to the right and turning the gear 121 counterclockwiseabout shaft 120 thereby advancing the tape 11 two character positions tothe left as the sprocket 118 is turned on the shaft 120counterclockwise.

While probe pressure drives the air reader, such probing does not occuruntil after the pressure on the purge line 76 has been generated bymeans of driving the aligner latch valve 74 to its upper position afterthe exchange is terminated. The adjustment of the pilot valves duringthe probe cycle will have been completed .well prior to that time; andwith the application of pressure on line 76, and the displacement of thepurge spool valve 98 to the left, the pressure applied on line 1 to theair pressure head 1 1 1 will have been blocked by the leftward land ofthe spool valve 98. This turns off pressure to the reader head 111.

During the period the rack rotates the drive gear, there is asubstantial separating force between the rack and gear due to thepressure angle of the gear teeth (20) which is supported by the toggleshaft.

With pressure removed from the left end of the toggle valve, its springwill drive it to the left rotating the toggle lever 126 to its initialposition. The toggle valve will expose port 139 to its port 281, therebyremoving pressure from the left-hand side of the drive piston allowingit and its rack to return to its initial position by the reaction of itsspring.

During a tape advance cycle described in the above application, thepilot valves of the hydraulic system must be physically locked bypressure in line 88 from responding to the tape holes 28 as they moveunder the air reader head 111, and at the same time sense hoses l2,diaphragms 102 and air reader ports must be flushed out with a reverseair blast to purge the air sense system of any contamination from theprevious read cycle. Line 76 to the purge control and isolating valves98, respectively, causes both valves to move to the left, valve 98moving against the reaction of its spring 108. The transfer of themultiple land isolating valve 98 will expose all of the purge lines 101to pressure port of the transferred purge control valve 99 and, at thesame time, shut off the air pressure to the air manifold 1 10 by thescissoring action of the extreme left-hand land of the isolating valve98.

The port 100 of the purge control valve exposed to its 10 psig port 109provides a reverse air flow pressure. The pressure blows air in reversethrough the diaphragm chambers, sense hoses and the air reader headports. Foreign matter if any is expelled between the air reader head andtape to the atmosphere. Following this purge cycle, the entire readingcircuit and diaphragms must be depressurized before releasing the lockeddiaphragm actuated pilot valves. To accomplish depressurization, thepurge control valve is returned to its initial position before thereturn of the isolating valve 98 seals off all the purge hoses 101.

A time delay network consisting of an orifice in series with move delaypiston 68 controls return of the purge control valve 99 to its initialposition to expose all the purge hoses to the atmosphere through port281. Again at the end of the tape advance cycle the aligner latch valve74 is restored to its initial position with the removal of the hydraulicsignal, exposing line 76 to the reservoir allowing the tape advancecircuit and isolating valve to reset to their initial positions.

The reset of the isolating valve will admit air pressure to the airmanifold and, at the same time, seal the individual purge hoses toprevent cross talk. With the release of the locking pressure from thepilot valves, it

will allow the diaphragms to respond to a hole in the tape causing thetransfer of the pilot valve against the reaction of its spring.

An advantage of the above described pneumatic tape reader is that it hasa minimal number of moving parts, is capable of reading two characterssimultaneously,

and in contrast with the type of reader which had been required inconnection with this type of system before, eliminates the need for acharacter buffer storage unit. Use of pressure instead of vacuum sensingof the tape holes minimizes the problem of contamination and costlyfiltration. I

AIR HYDRAULIC INTERFACE From the lines 12 of the air reader 10connection is made, as described above, to the lines 12 to thediaphragms 102 in FIG. 2C. When pressure is applied to a line 12, thenone of the corresponding diaphragms 102 operates to drive its pilotvalve 85 left. This drives the associated latch valve 14 left, duringpresent of pressure on probe line 81, as the line 84 connects to theright-hand side of the central land of the pilot valve 85. Pressure isapplied to the right end of latch valve 14. Latch valve 14-16 on theleft-hand side of FIG. 2C. The numeral 14l6 indicates that the latchvalve is connected to the 16 inch piston adder 140 by lines 141 and 142.The right hand one of the lines 142 has pressure applied to it when thepilot valve is actuated by the reader. Line 142 passes through thevelocity control valve, and pressure on line 94, reduces the orificethrough the velocity control valve for the piston adders. Exchangeoccurs fast; as described below. First, the load is braked and inessence disconnected from the piston adders so no moving or collapsingof the heavy load occurs during exchange. Secondly, orifices regulatethe rate of flow of fluid to the adder drive. Such regulation isafforded in two ways. First opening or closing of the bypass poppet 37controls the effective orifice size to control flow. Second, a velocitycontrol valve controls flow. The velocity control valve is controlledthrough line 94 from hydraulic logic 20.

What is claimed is:

1. An apparatus for reading perforated media including pneumatic sensingmeans,

pneumatic coupling means for coupling pneumatic signals between inputterminals of said coupling means and said pneumatic sensing means,

the improvement comprising integral pneumatic purging means forproviding periodic pneumatic purging cycles for purging fluid throughsaid pneumatic coupling means in the reverse direction from saidpneumatic input signals to eject foreign material from said means forcoupling,

and control means for alternating said pneumatic purging cycles withpneumatic coupling cycles, said pneumatic coupling cyclescomprisingintervals during which pneumatic input signals are coupled by saidcoupling means to said pneumatic sensing means.

2. Apparatus in accordance with claim 1 wherein said control meansoperates inhibiting valve means for preventing sensing by said pneumaticsensing means dur ing operation of said purging means.

3. Apparatus in according with claim 2 including terminating means forterminating purging by said purging means a predetermined period of timeprior to termination of operation of said inhibiting valve means inorder to prevent residual purging pressure from actuating said pneumaticsensing means.

4. Apparatus in accordance with claim 1 including a source of pneumaticreading fluid connected to an outlet directed at said input terminals ofsaid pneumatic coupling means, and valving means for blocking said 7source from said outlet during purging by said purging means.

5. Apparatus in accordance with claim 3 wherein said terminating meanscomprises a time delay circuit and a pressure control valve.

6. Apparatus in' according with claim .1 wherein said purging meansincludes means for blocking cross talk between separate pneumaticcoupling means between pneumatic coupling cycles.

7. An air reader including a plurality of sensing lines,

a source of pneumatic pressure communicating with a pneumatic manifoldspaced above the input ends of said sensing lines,

plurality of pneumatic diaphragms responsive to varying pressure in saidsensing lines each having an input chamber and coupled to a means forsensing displacement of a said diaphragm from a predetermined position,each of said diaphragms being biased to a said predetermined position, asaid sensing line connected to each said diaphragm input chamber, anisolating valve including a manifold having an outlet for fluidconnection with each diaphragm input chamber, said valve including aland for closing each outlet in a blocking position of said valve,

means for biasing said isolating valve to said blocking position with aseparate land arresting communication between said isolating valvemanifold and each of said outlets from said valve,

each of said outlets being connected to an input chamber for adiaphragm,

a purging source of pneumatic fluid under pressure connected to saidisolating valve manifold under control of said isolating valve forproviding relatively high velocity air flow through said diaphragm inputchambers and through said sensing lines to said input ends thereof andtherethrough for purging therefrom foreign matter contained therein.

8. Apparatus in accordance with claim 7 including a purge control valvemeans and time delay means associated therewith connected between saidpurging source and said isolating valve for blocking purging flow -apredetermined time period after initiation of a cycle of purging flow.

9. A method for reading perforated media pneumatically including,

coupling pneumatic input signals to pneumatic sensing means throughpneumatic coupling means,

the improvement comprising using integral pneumatic purging means forperiodically purging fluid through said pneumatic coupling means in thereverse direction from the direction from which the pneumatic inputsignals are applied in order to eject foreign material from saidpneumatic coupling means,

and using control means for alternating the pneumatic purging cycleswith pneumatic coupling cycles, said pneumatic coupling cyclescomprising intervals during which pneumatic input signals are cou pledby said coupling means to said pneumatic sensing means.

1. An apparatus for reading perforated media including pneumatic sensingmeans, pneumatic coupliNg means for coupling pneumatic signals betweeninput terminals of said coupling means and said pneumatic sensing means,the improvement comprising integral pneumatic purging means forproviding periodic pneumatic purging cycles for purging fluid throughsaid pneumatic coupling means in the reverse direction from saidpneumatic input signals to eject foreign material from said means forcoupling, and control means for alternating said pneumatic purgingcycles with pneumatic coupling cycles, said pneumatic coupling cyclescomprising intervals during which pneumatic input signals are coupled bysaid coupling means to said pneumatic sensing means.
 2. Apparatus inaccordance with claim 1 wherein said control means operates inhibitingvalve means for preventing sensing by said pneumatic sensing meansduring operation of said purging means.
 3. Apparatus in according withclaim 2 including terminating means for terminating purging by saidpurging means a predetermined period of time prior to termination ofoperation of said inhibiting valve means in order to prevent residualpurging pressure from actuating said pneumatic sensing means. 4.Apparatus in accordance with claim 1 including a source of pneumaticreading fluid connected to an outlet directed at said input terminals ofsaid pneumatic coupling means, and valving means for blocking saidsource from said outlet during purging by said purging means. 5.Apparatus in accordance with claim 3 wherein said terminating meanscomprises a time delay circuit and a pressure control valve. 6.Apparatus in accordance with claim 1 wherein said purging means includesmeans for blocking cross talk between separate pneumatic coupling meansbetween pneumatic coupling cycles.
 7. An air reader including aplurality of sensing lines, a source of pneumatic pressure communicatingwith a pneumatic manifold spaced above the input ends of said sensinglines, a plurality of pneumatic diaphragms responsive to varyingpressure in said sensing lines each having an input chamber and coupledto a means for sensing displacement of a said diaphragm from apredetermined position, each of said diaphragms being biased to a saidpredetermined position, a said sensing line connected to each saiddiaphragm input chamber, an isolating valve including a manifold havingan outlet for fluid connection with each diaphragm input chamber, saidvalve including a land for closing each outlet in a blocking position ofsaid valve, means for biasing said isolating valve to said blockingposition with a separate land arresting communication between saidisolating valve manifold and each of said outlets from said valve, eachof said outlets being connected to an input chamber for a diaphragm, apurging source of pneumatic fluid under pressure connected to saidisolating valve manifold under control of said isolating valve forproviding relatively high velocity air flow through said diaphragm inputchambers and through said sensing lines to said input ends thereof andtherethrough for purging therefrom foreign matter contained therein. 8.Apparatus in accordance with claim 7 including a purge control valvemeans and time delay means associated therewith connected between saidpurging source and said isolating valve for blocking purging flow apredetermined time period after initiation of a cycle of purging flow.9. A method for reading perforated media pneumatically including,coupling pneumatic input signals to pneumatic sensing means throughpneumatic coupling means, the improvement comprising using integralpneumatic purging means for periodically purging fluid through saidpneumatic coupling means in the reverse direction from the directionfrom which the pneumatic input signals are applied in order to ejectforeign material from said pneumatic coupling means, and using controlmeans for alternating the pneumatic purging cycles with pneumaticcoupling cycles, said pneumatic coupling cycles comprising inTervalsduring which pneumatic input signals are coupled by said coupling meansto said pneumatic sensing means.